Apparatus for coating coiled springs



Oct. 27, 1964 Filed Aug. 13, 1962 B. E. LOVE APPARATUS FOR COATING COILED SPRINGS 2 Sheets-Sheet 1 Oct. 27, 1964 B. E. LOVE 3,154,433

APPARATUS FOR COATING COILED SPRINGS Filed Aug. 15, 1962 2 Sheets-Sheet 2 United States Patent O "ce 3,154,433 APPARATUS FOR COATING COILED SPRINGS Bernard Eric Love, Pedmore, Stourbridge, England, assigner to Joseph Lucas (Industries) Limited, Birmingham, England Filed Aug. 13, 1962, Ser. No. 216,579 3 Claims. (Cl. 118-59) It is known to apply a coating of nylon or other thermo plastic to the convolutions of a coiled spring in order to enhance the wearing properties of the spring, and to reduce friction between the spring and a part within which it must move. However, heretofore it has been usual to apply the coating over the whole surface of each convolution, by immersing the spring within an agitated plastic powder. Such an arrangement reduced the amount by which the spring can be compressed due to the presence of the double coating between each pair of adjacent convolutions, and the object of the present invention is to provide a convenient method and apparatus whereby a plastic coating can be applied to the outer peripheral surface only of each convolution.

A method according to the invention comprises heating the spring, rolling the spring in its heated condition over a surface on which is a layer of powdered plastic so as to cause the plastic to adhere to the outer peripheral surface of the convolutions of the spring, and subsequently sintering the adhering plastic.

Apparatus according to the invention comprises in combination a furnace, means for feeding the springs in single tile downwardly into the furnace, a slide extending transversely across the lower end of the furnace, said slide having formed therein an aperture adapted to receive the lowermost spring from the furnace, a platform extending in substantially parallel relationship below the slide whereby to support a spring within said aperture, means for reciprocating the slide whereby successive springs will be caused to roll upon said surface before discharge therefrom, and means for supplying powdered thermo-plastic to the platform.

In the accompanying drawings FIGURE 1 is a partsectional side view and FIGURE 2 an end View illustrating apparatus in accordance with one example of the invention, whilst FIGURE 3 is a plan of part of FIG- URE 1.

Referring to the drawings there is provided an electrically heated furnace 4 having an opening at its upper end. Extending downwardly into this furnace is an inclined track 5 comprising a pair of spaced rails which may be interconnected at their outer ends. The sp-rings 6 to be treated each have inserted within their ends respectively a pair of plugs 7 having integral pegs adapted to roll upon the track, the arrangement being such that springs thus provided can be placed between the rails with the pegs on the rails, and in this position a plurality of springs can be fed downwardly into the furnace by gravity in single file. Moreover, the width of the furnace 4 is such that the springs will rest singly one upon another in the furnace as shown in FIGURE 1.

Beneath the furnace is a body part S the upper surface of which defines a downwardly inclined platform 9. The platform 9 serves to guide a reciprocable slide 10 in which is formed an aperture 11 (FIGURE 3) shaped to accommodate a spring with its plugs. The slide is reciprocable by means of a double-acting pneumatic ram 12 having its cylinder secured to the body part S and its piston secured to the slide 10. The slide is movable by the ram 12 between a loading position (not shown) in which the aperture 11 is situated beneath the furnace to receive the lower-most spring therefrom, and the unloading position illustrated in which Ithe aperture 11 is located beyond an edge of the platform 9 so that the spring can fall from 3,154,433 Patented Oct. 27, 1964 the aperture. The plugs 7 are made of slightly greater diameter than the springs, so that during movement between the loading and unloading positions, a spring located in the aperture will be caused to roll upon the upper surface of the platform 9.

Adjacent the furnace 4 is a hopper 13 within which is contained powdered nylon or other powdered thermoplastic. The hopper 13 includes an angularly movable drum 14 having a recess 15 in its periphery. The drum is angularly movable on a shaft 16 to which is secured one end of a link 17. The other end of the link 17 has a roller 18 slidable in a slot in an arm 19 secured to the slide 10. The arrangement is such that each time the slide is moved to the loading position the drum 14 will be moved angularly and a predetermined amount of thermoplastic deposited in the recess 15 will be fed onto the platform 9. The depth of this layer is determined by a doctor blade 2) at the leading edge of the slide 10 as the latter moves from the loading to the unloading position. Moreover, the timing of the reciprocations of the slide 10 are so arranged with respect to the temperature of the furnace that, provided the furnace has been maintained filled, each spring will be at a temperature of about 300 C. during the time it is rolled in the layer of powdered plastic on the platform 9. This causes the plastic to adhere to the outer peripheral surfaces of the convolutions of the spring.

Below the edge of the platform 9 from which the springs are to be discharged is positioned a device for removing the springs after they have been treated. The device comprises a track 21 on which the pegs extending from the plugs 7 can roll, and an endless conveyor (part of which is shown at 22). The conveyor 22 incorporates a plurality of arms 23 which are arranged to lift the springs from the track 21, and the conveyor is traversed at such a speed that by the time the springs are removed frorn the conveyor they will have cooled suliiciently to enable them to be handled without removing the powdered plastic adhering thereto.

Subsequently the springs discharged from the conveyor are removed by hand, or by mechanical means to au oven in which the plastic coating is sintered by sustaining the springs at a temperature of, for example, Z50-270 C. for about 11/2 minutes.

In practice the springs would be de-greased and cleaned prior to being fed to the furnace.

Having thus described my invention what I claim as new and desire to secure by Letters Patent is:

1. Apparatus for applying a coating of thermoplastic to lthe outer peripheral surface of each convolution of a coiled spring, comprising in combination a body defining a downwardly inclined platform, a furnace mounted on said body above said platform, a slide slidable on said platform, said slide having an aperture extending inwardly from the lower end thereof, means acting between the body and the slide for reciprocating the slide between an unloading position in which said aperture is beyond the lower end of the platform and said slide closes the lower end of the furnace, and a loading position in which said aperture is below the lower end of the furnace, means for feeding springs in single le downwardly into the furnace, the lowermost spring in said furnace falling into said aperture and resting on the platform when the slide is moved to said loading position, means on said body for feeding powdered thermoplastic to said platform, whereby by a spring in said aperture is rolled in the thermoplastic when the slide is moved towards said unloading position, and means on said body for receiving coated springs falling from the lower end of said platform when the slide reaches said unloading position.

2. Apparatus for applying a coating of thermoplastic to the outer peripheral surface of each convolution of a coiled spring, comprising in combination a body defining a downwardly inclined platform, a furnace mounted on said body above said platform, a slide slidable on said platform, said slide having an aperture extending inwardly from the lower end thereof, a doctor blade closing the end of said aperture, means acting between the body and the slide for reciprocating the slide between an unloading position in which said aperture is beyond the lower end of the platform and said slide closes the lower end of the furnace, and a loading position in which said aperture is below the lower end of the furnace, means for feeding springs in single file downwardly into the furnace, the lowermost spring in said furnace falling into said aperture and resting on the platform when the slide is moved to said loading position, means on said body for feeding powdered thermoplastic to said platform at a position in advance of said slide when said slide is in said loading position, said doctor blade spreading said thermoplastic over said platform when the slide is moved towards said unloading position, whereby a spring in said aperture is rolled in the thermoplastic when the slide is moved towards said unloading position, and means on said body for receiving coated springs falling from the lower end of said platform when the slide reaches said unloading position.

3. Apparatus for applying a coating of thermoplastic to the outer peripheral surface of each convolution of a coiled spring, comprising in combination a body dening a downwardly inclined pla-tform, a furnace mounted on said body above said platform, a slide slidable on said platform, said slide having an aperture extending inwardly from the lower end thereof, a doctor blade closing the open end of said aperture, a double-acting pneumatic ram acting between said body and said slide for reciprocating a slide between an unloading position in which said aperture is beyond the lower end of the platform and said slide closes the lower end of the furnace, and a loading position in which said aperture is below the lower end of the furnace, means for feeding springs in single file downwardly into the furnace, the lowermost spring in said furnace falling into said aperture and resting on the platform when the slide is moved to said loading position, a hopper supported by said body, means operated by said slide on movement of said slide from said unloading position to said loading position for depositing a predetermined amount of thermoplastic on said platform in advance of said slide when said slide is in the loading position, said doctor blade spreading the thermoplastic over the platform when the slide is moved from said loading position to said unloading position, whereby a spring in said aperture is rolled in the thermoplastic when the slide is moved towards said unloading position, and means on said body for receiving coated springs falling from the lower end of said platform when the slide reaches said unloading position.

References Cited in the tile of this patent UNITED STATES PATENTS 597,835 Blackwell Jan. 25, 1898 1,198,020 Graham Sept. 12, 1916 1,586,353 Colegrove May 25, 1926 2,005,089 Krebs June 18, 1935 2,737,461 Heisler et al Mar. 6, 1956 2,803,332 Hagerman Aug. 20, 1957 2,945,471 Harrold July 19, 1960 2,972,947 Fitzsimmons et al Feb. 28, 1961 2,995,482 Boyce et al Aug. 8, 1961 3,052,210 Hughes Sept, 4, 1962 3,074,808 Harrison Jan. 22, 1963 

1. APPARATUS FOR APPLYING A COATING OF THERMOPLASTIC TO THE OUTER PERIPHERAL SURFACE OF EACH CONVOLUTION OF A COILED SPRING, COMPRISING IN COMBINATION A BODY DEFINING A DOWNWARDLY INCLINED PLATFORM, A FURNACE MOUNTED ON SAID BODY ABOVE SAID PLATFORM, A SLIDE SLIDABLE ON SAID PLATFORM, SAID SLIDE HAVING AN APERTURE EXTENDING INWARDLY FROM THE LOWER END THEREOF, MEANS ACTING BETWEEN THE BODY AND THE SLIDE FOR RECIPROCATING THE SLIDE BETWEEN AN UNLOADING POSITION IN WHICH SAID APERTURE IS BEYOND THE LOWER END OF THE PLATFORM AND SAID SLIDE CLOSES THE LOWER END OF THE FURNACE, AND A LOADING POSITION IN WHICH SAID APERTURE IS BELOW THE LOWER END OF THE FURNACE, MEANS FOR FEEDING SPRINGS IN SINGLE FILE DOWNWARDLY INTO THE FURNACE, THE LOWERMOST SPRING IN SAID FURNACE FALLING INTO SAID APERTURE AND RESTING ON THE PLATFORM WHEN THE SLIDE IS MOVED TO SAID LOADING POSITION, MEANS ON SAID BODY FOR FEEDING POWDERED THERMOPLASTIC TO SAID PLATFORM, WHEREBY A SPRING IN SAID APERTURE IS ROLLED IN THE THERMOPLASTIC WHEN THE SLIDE IS MOVED TOWARDS SAID UNLOADING POSITION, AND MEANS ON SAID BODY FOR RECEIVING COATED SPRINGS FALLING FROM THE LOWER END OF SAID PLATFORM WHEN THE SLIDE REACHES SAID UNLOADING POSITION. 